Environmental lighting, particularly outdoor lighting, is well known in commercial or public settings such as parks and schools. Such lighting is also popular in residential applications, both to enhance the appearance and safety of the outdoor area and for security, to illuminate dark areas around a building or in a yard which may provide hiding places and unobserved entry points for intruders.
Landscape and outdoor lighting systems include one or more lighting fixtures which are connected to either a 12 V transformer or a standard 120 VAC line. Some lighting fixtures enclose a halogen lamp or conventional bulb within a housing, and include a reflector assembly and a lens or window within the housing. These fixtures may be used for highlighting features such as trees or statues, i.e., up-lighting or for pathway or ground lighting. Other fixtures, used almost exclusively in down-lighting applications, may have an open aspect, where the reflector, and sometimes the lamp and socket are open and directed toward the ground. These fixtures tend to be used in larger quantities within a lighting system since they are typically less expensive than the closed fixtures and are capable of washing large expanses of open area with glare-free light, e.g., pathways, driveways, patios, ground cover plants, and for perimeter lighting.
Pathway downlighting fixtures typically include a hood or cowl shaped in the form of a bell, half-shell, cone, tulip, or pyramid that surrounds the lamp except for the lower end of the cowl from which the light emanates. In addition to preventing escape of light in an upward direction, the inner surface of the cowl acts as a reflector to optimize the amount of light directed toward the desired target area.
Outdoor light fixtures are prone to dirt build-up and/or corrosion that can diminish light output and accelerate deterioration and, ultimately, failure of the fixture.
An example of a pathway lighting fixture that addresses this problem is provided in U.S. Pat. No. 6,799,869 of Beadle, which is incorporated herein by reference. The fixture has an open face, with the bulb exposed to the elements, while providing a substantially water-tight seal around the base of the bulb and the socket to reduce damage from moisture and dirt intrusion. A collar that lines the inner surface of the fixture's hood performs the seal function at the same time it serves as a light reflector to increase the efficiency of the light output from the bulb. The type of fixture for which the open construction is appropriate generally uses a common low wattage incandescent bulb that generates some heat, but not so much heat that there is a significant fire risk or likelihood of the hot bulb shattering when it becomes wet. The lighting produced by these fixtures is generally quite diffuse. Such a fixture construction would not be appropriate for use with halogen lamps, which produce much higher intensity light, but also create a significant risk of fire if any flammable material comes into contact with the hot lamp. Contamination is also more likely to negatively impact the life of the lamp.
In closed fixtures, the effects of dirt build-up and/or oxidation can be reduced by sealing the lamp within a clear or translucent cylinder to create a moisture-proof chamber. This also removes the risk of physical contact with the bulb. To achieve the desired seal, the upper edge of the cylinder is often permanently attached to the hood using epoxy or silicone adhesive. Any accumulation of material on the cylindrical lens can be easily wiped away to restore full illumination capability. A drawback of the closed fixture design is that one must disassemble the housing by separating the lens from a base portion to access the lamp for replacement. Another issue with closed fixtures is that the lens can break or crack. Since the lens is glued to the hood, the entire hood/lens assembly must be replaced if one wishes to ensure a well-sealed fixture. An exemplary closed fixture is described in U.S. Pat. No. 6,874,905 of Beadle, which patent is incorporated herein by reference. In addition to being costly to replace both the lens and metal hood, introduction of a new hood into an established lighting system can detract from the aesthetics of the system since the new hood will not match the other fixtures because is has not weathered or oxidized, for example, to a verde finish in the case of copper.
The need remains for a pathway light fixture that is attractive, resists breakdown in an outdoor environment, is easy to manufacture and service, and includes easily replaced critical components while still maintaining a good quality seal.